Boreless compressor wheels are characterized by a hub that extends in an axial direction with first and second opposite faces and a plurality of blades that extend radially on the first face. In operation, the wheel is configured to rotate about its axis so that the blades move, or are moved by, air passing proximate to the first face of the wheel. For example, the wheel can be mounted in a housing with a connection portion on the second face of the wheel engaged to a shaft so that as the shaft and the wheel are rotated, the blades push air through the housing. As the name suggests, a boreless compressor wheel does not have a bore that extends through the hub for mounting. Instead, the connection portion on the second face can extend from the face or can define an aperture that does not extend to the first face of the wheel.
During the manufacture of a boreless compressor wheel, the wheel must be sufficiently supported so that the faces and/or blades can be machined or otherwise formed to desired tolerances. Therefore, the compressor wheel is supported to resist the forces on the wheel associated with the machining or other forming operations.
For example, during a conventional manufacturing process, the boreless compressor wheel is supported in a chuck and turned, i.e., machined, in a lathe.
The chuck receives at least part of the blades and the first face of the wheel so that the wheel can be sufficiently supported while the lathe is used to partially form or finish the exposed faces and/or blades. The wheel is then removed from the chuck and secured in a second chuck that supports the wheel by other portions to expose the portions that were previously inaccessible for machining. Thus, those portions of the first face and blades that are obstructed by the first chuck can be formed while the wheel is secured in the second chuck. However, the use of successive machining operations increases the time required for forming or finishing the wheel. Further, the cost of the two chucks required for securing the wheel increases the cost of the wheels.
Thus, there exists a need for an improved fixture for supporting a boreless compressor wheel or other rotatable member. Preferably, the fixture should be capable of securing the member so that the member can be machined or otherwise formed to predetermined dimensions within predetermined tolerances. Further, the fixture should secure the member without obstructing access to portions of the member that are to be machined, for example, the blades of a boreless compressor wheel, so that the member can be machined without removing the member from the fixture.